Re: [stella] What's magic about a byte?

Subject: Re: [stella] What's magic about a byte?
From: Chris Wilkson <ecwilkso@xxxxxxx>
Date: Wed, 13 Apr 2005 23:57:20 -0400
On Wed, 13 Apr 2005, Ruffin Bailey wrote:

> Why would the number of bits in a byte have to have anything to do with
> powers of 2?  The max number, whether 7 bit, 13 bit, or 8 bit would
> still be a binary number.  ??

Because decoders and encoders using bits as control lines will always
address 2^n locations.  Either you implement them, or you don't.  But
if you need 5 states, you need 3 bits to represent that.  Then you have
created 3 bogus states.  You need to define them or else "Bad Things"
can happen.  You can define them by hardwiring, but you might as well
make them useful if you can.

In the case of decimals digits, you need 4 bits to encode each character
with.  If your system is already 6 bits, just to encode the text characters,
you're wasting 2 bits when doing BCD.  You might as well make your word
8 bits wide so you can encode 2 digits without waste.


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